A photograph of two participants in the Bedrest Study


    NASA organizes the bed rest studies into campaigns. These campaigns are composed of subject volunteers medically cleared to participate in the Standard Measures and research tests designed for each campaign. Every campaign and science complement has been reviewed and approved by the NASA JSC Committee for the Protection of Human Subjects, the UTMB Institutional Review Board, the UTMB GCRC Advisory Committee and any required investigator review boards. All subjects have provided informed consent to participate in the campaign.

    Standard Measures are a series of multi-disciplinary tests and reflect the same assessments as those performed on ISS astronauts as part of their medical evaluation. The results from these assessments:

    • Became part of the medical monitoring of the subjects
    • Increased the description of the physiologic responses to bed rest in humans
    • Provided a basis to compare bed rest results with results from flight investigations
    • Served as control data for the countermeasures and provided ancillary data to individual investigators

    The Standard Measures that were run on all subjects who participated throughout the campaigns included:

    1.     Neurocognitive Assessment
    Cognitive changes are reported and measured during spaceflight and in simulations. Cognitive function of all subjects is measured before, during, and after bed rest using the same neurocognitive assessment tool required for crew members flying aboard long-duration spaceflight missions. Sustained concentration, verbal working memory, attention, short-term memory testing, spatial processing, and math skills are assessed by this computer-based tool.
    Clinical laboratory assessment Clinical Laboratory Assessment

    2.     Clinical Laboratory Assessment
    The Clinical Laboratory provides fundamental medical hematologic, chemical, immunologic and urinary biochemical analyses. This laboratory provides the capability to perform sample analysis from the various investigations.

    3.     Bone Mineral Density
    These tests obtain measures of bone mineral density before and after exposure to long-duration bed rest to assess the effects of various proposed countermeasures on disuse bone loss. A standard clinical technique Bone Mineral Densityknown as dual-energy X-ray absorptiometry (DEXA) and a peripheral quantitative computed tomography (pQCT) are used to obtain these measurements. Bone mineral density decreases in bone sites such as the hip, spine, pelvis, and heel when loads on the skeleton are reduced. Bed rest has
    Bone mineral density testing Bone Mineral Density
    been shown to be a suitable analog for spaceflight when studying changes in bone. When comparing spaceflight results of bone loss to bed rest, the skeletal sites affected and the underlying mechanism of bone loss are the same.

    4.     Clinical Nutritional Assessment
    The goal of this protocol is to assess the nutritional status of subjects before, during, and after bed rest. This helps determine the response of nutrition and related systems to bed rest, and to evaluate countermeasure effectiveness in preventing negative side effects of simulated weightlessness, and additionally to assess whether countermeasures for one system have a negative impact on another system.
    Clinical nutritional assessment Clinical Nutritional Assessment

    Maintaining dietary intake and nutritional status is essential to compare results from different bed rest studies. Maintaining crew health is imperative for long-duration space missions, and adequate nutrition will be critical for this effort. To provide nutritional recommendations to crew members for long-duration space travel, NASA needs to better understand how nutritional status and general physiology are affected by the microgravity environment. Bed rest is a well-accepted ground-based model of this environment.

    In this nutritional status assessment protocol, blood and urine samples are analyzed to provide information on general chemistry, as well as to assess markers of hematologic, vitamin, and mineral status. Markers of oxidative damage and of bone metabolism (formation and breakdown) also are measured. Detailed dietary intake analysis and anthropometric information are also evaluated to better understand the human response to bed rest and countermeasures.

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